According to a first main aspect the invention relates to a method for forming a corner join at a comer of a box,
wherein the box has been/is formed from a blank comprising a base panel, a first side wall panel joined to said base panel via a first panel fold line, a second side wall panel joined to said base panel via a second panel fold line and a joining flap joined to the first side wall panel via a joining flap fold line;
wherein the joining flap fold line essentially determines the corner when the corner join has been formed;
wherein the first and second panel fold lines and the joining flap fold line essentially intersect one another at the bottom of the comer at the base panel and the first and second side wall panels extend as far as the corner when the comer join has been formed, and
wherein the first side wall panel is joined to the second side wall panel by placing the joining flap such that it overlaps the second side wall panel in an overlap area on the second side wall panel and fixing it thereto.
A method of this type is generally known. With this arrangement, both according to the prior art and also according to the invention still to be described below, the joining flap can either be placed with its inside against the outside of the second side wall panel and fixed thereto, for example by gluing or stapling, or placed with its outside against the inside of the second side wall panel and fixed thereto, for example by gluing or stapling. Placing the joining flap with the outside against the inside of the second side wall panel is preferred since the box to be obtained is then as flat as possible on the outside, which is practical for further manipulation and further handling of the box.
One problem with corner joins formed in this way is that the box is not completely gas- and liquid-tight at the corner. In general, a free flow channel from the interior of the box to the exterior of the box and vice versa remains through the corner point of the corner join located at a base panel. This is, in particular, a significant disadvantage when forming boxes which have to have a controllable interior atmosphere since the more or less free, uncontrolled communication between the interior and the exterior of the box disturbs the control of the atmosphere in the interior of the box and makes this appreciably more difficult and frequently even impossible.
According to the first main aspect, the invention relates in particular to a method of the type mentioned at the start, wherein, in addition, a mastic-like filler is applied, preferably in the form of a bead, in or on the inside of the second panel fold line, at the location of the overlap area.
Such a method is disclosed in FR 2 178 687, which corresponds to NL-A 73.03732. NL-A 73.03732 discloses, in FIGS. 4 and 5 and the associated part of the description, a method corresponding to the pre-characterising clause of Claim 1. According to NL-A 73.03732 a filling consisting of a tacky mixture is injected into each of the overlap join locations after the box has been fully folded and after the side wall panels have been fixed to one another by means of the joining flap, in order to make the box light-tight in the corners. This method has a number of disadvantages. As a result of injecting the filling consisting of a tacky mixture only after setting up the box and fixing the side wall panels to one another an additional subsequent operation is required which prolongs the time needed for production of one box and thus makes the production speed slower. A further disadvantage is that although a light-tight corner join can allegedly be achieved by the method according to NL-A 73.03732, it is not possible to produce a reliable light-tight corner join by this method.
The aim of the present invention is to provide an improved method for forming a corner join at a corner of a box, in particular a box for use under so-called controlled atmospheric conditions, which method results in an essentially gas- and/or liquid-tight corner join.
The abovementioned aim is achieved according to the invention in that the mastic-like filler is applied to the blank before the joining flap is placed against the second side wall panel and fixed thereto. Said mastic-like filler can be applied to the flat blank before folding the box, but it is also entirely conceivable that the mastic-like filler is applied after partially folding the box from the blank prior to fixing the joining flap to the second side wall panel. Especially in the case where the joining flap is placed with its outside against the inside of the second side wall panel and is fixed thereto, it is also conceivable that the mastic-like filler is initially applied to the underside of the joining flap and that the mastic-like filler is automatically transferred into or onto the inside of the second panel fold line at the location of the overlap area on placing the joining flap against the second side wall panel and pressing onto the latter for fixing, for example in that the mastic-like filler has been applied to the downward-facing bottom edge of the joining flap or in that the mastic-like filler has been applied in excess to the bottom of the outside of the joining flap and on pressing the joining flap against the inside of the second side wall panel is expressed between the two and transferred into or onto the inside of the second panel fold line. The essential feature is that the mastic-like filler, which, as can be seen from the above, can thus also be the adhesive for joining the joining flap to the second side wall panel, forms a sealing plug or seal, which, in particular, ensures that the join is sealed from the outside via the socalled corner point, that essentially is located on or close to the point of intersection of the first panel fold line, the second panel fold line and the joining flap fold line, towards the interior of the box and vice versa, by the mastic-like filler, which if appropriate can also be an optionally setting adhesive. Because the mastic-like filler is applied to a suitable position on the blank even before the joining flap is placed against the second side wall panel and is fixed thereto, this operation can be carried out simultaneously with another operation for forming the box, in particular if the formation of a box from a blank is automated. The mastic-like filler can be applied simultaneously with the application of further adhesive tracks or adhesive strips or simultaneously with certain folding operations. A further advantage of the application of the mastic-like filler prior to fixing the joining flap to the second side wall panel is that the air seal, or at least the reliable and simple production thereof, can be improved in this way. Specifically, the mastic-like filler will then be expressed on producing the corner join, that is to say joining the joining flap and the second side wall panel to one another, and will thus be distributed over a larger area and improve the liquid and gas seal. Said expression takes place in particular if the bottom edge of the joining flap which faces the base panel is in contact with or close to the base panel when the box is in the assembled state.
According to an advantageous embodiment of the invention, the blank is based on board or paper. However, the essence of the invention can also very readily be applied when forming corner joins in a box which is formed from a blank of a completely different type of material, such as, for example, plastic or metal.
In order to obtain a good and reliable seal it is particularly advantageous according to the invention if the filler is at least applied in or on that end of the second panel fold line which faces towards the corner.
It is particularly advantageous according to the invention if the mastic-like filler is applied to the blank before the first side wall panel is raised with respect to the base panel by folding about the first panel fold line. This is because the blank is then relatively most easily accessible for administration means for applying the mastic-like filler. Especially in the case where, in the raised position, the joining flap is located on the inside of the box and extends as far as or very close to the base panel and the filler has been applied in or to that end of the second panel fold line that faces towards the corner and/or to the bottom edge of the joining flap which, in the raised position, faces the base panel, a good gas- and liquid-tight corner join can then be achieved by pressing the bottom edge of the joining flap into the mastic-like filler when raising the first side wall panel and thus laterally forcing out excess filler.
Since the second panel fold line can form a channel to the corner, it is furthermore advantageous according to the invention if the filler is applied as a bead, which in particular extends in or on the inside of the second panel fold line. In this way it can be substantially ensured that the seal of, ultimately, the corner is further ensured by substantially reliable sealing of the channel towards that point. In this context it is particularly advantageous if the bead extends, preferably uninterrupted, along essentially the entire overlap area. If the joining flap extends as far as the base panel or to very close to the base panel, a good seal/closure between the underside of the joining flap and the base panel can in particular also be ensured in this way. In this case it is not absolutely essential under all circumstances for the mastic-like filler also to be applied directly in or to that end of the second panel fold line that faces towards the corner, although this is still advantageous.
In order further to ensure a tightly sealed, in particular gas- and liquid-tight sealed corner join, especially with regard to the reliability of the seal, it is advantageous according to the invention if the outside of the joining flap is provided with at least one adhesive strip which extends uninterrupted from the bottom edge of the joining flap, which faces towards the base panel, to the top edge of the joining flap, which faces away from the base panel, and if the adhesive strip is applied such that, when the corner join has been formed, it abuts the filler at the bottom edge of the joining flap, said filler preferably extending uninterrupted from said location of abutment to into the corner, at least when the corner join has been formed. This prevents a connecting channel, running towards a corner point, for gas/liquid communication between the interior and the exterior of the box from being able to form between the joining flap and the second side wall panel. The reason for this lies in particular in the fact that the mastic-like filler is also expressed when producing the corner join, which reliably ensures the abutment of the filler and the adhesive strip.
The production or leaving behind of such a connecting or communication channel between the joining flap and the second side wall panel can be further prevented/counteracted independently of the solution outlined in the previous paragraph, or as a supplement thereto, if the inside of the second side wall panel is provided with at least one adhesive strip which extends uninterrupted from the filler to at least the top end of the overlap area, and preferably beyond this, and abuts the filler. The uninterrupted adhesive strip extending over the height (viewed relative to the base panel) of the overlap area can thus be/have been provided both at the location of the overlap area on the second side wall panel and on the joining flap or even on both. The reason for this lies in particular in the fact that the mastic-like filler is also expressed on producing the corner join, which reliably ensures the abutment of the filler on the adhesive strip.
If the second side wall panel has been provided with a second top flap which has been formed in one piece therewith and which is joined to the second side wall panel via a second top flap fold line, which runs parallel to the second panel fold line, and has been or is folded so that it points towards the inside of the box, it is then also highly advantageous according to the invention if a mastic-like filler is applied, preferably in the form of a bead, in or on the inside of the second top flap fold line, at the location of the overlap area. In a manner comparable to that in the case of the underside of the corner join, this prevents/counteracts a communication channel to the top corner point located at the top of the corner join from being able to form at the top of the corner join.
In this context the top corner point is in particular understood to be the region in the vicinity of the point of intersection of the joining flap fold line and the second top flap fold line.
In order to prevent/counteract the formation of a communication channel, or the risk of the formation thereof, between the joining flap and the second side wall panel through to the top corner point in the case of a second side wall panel having a top flap, it is furthermore advantageous according to the invention if the mastic-like filler has been applied in or on the second top flap fold line in such a way that, when the corner join has been formed, it abuts the top end of the adhesive strip, at least assuming that the adhesive strip has been applied to the joining flap and/or that the mastic-like filler in or on the second top flap fold line abuts the top end of the adhesive strip, at least assuming that the adhesive strip has been applied or has been co-applied to the second side wall panel.
If the first side wall panel has been provided with a first top flap which has been formed in one piece therewith and which is joined via a first top flap fold line, which runs parallel to the first panel fold line, to the first side wall panel and has been or is folded so that it points to the inside of the box so as partially to overlap the second top flap at the corner in an overlap zone, it is advantageous according to the invention, in order to improve the reliability of the gas-liquid-tight seal of the corner join, if a mastic-like filler is applied, preferably in bead form, in or on the inside of the first top flap fold line at the location of the overlap zone (between the first and second top flap). With such an embodiment the seal can also be improved instead of or in addition to this if the overlap zone is provided with at least one adhesive strip, either applied to the inside of the first top flap or applied to the outside of the second top flap, which adhesive strip extends uninterrupted over the entire overlap zone in a direction essentially parallel to that of the second top flap fold line.
With the method according to the invention the mastic-like filler used can advantageously be an adhesive, in particular an adhesive such as is customary for gluing blank sections of a blank when forming boxes. The adhesive will preferably be the same as that used for gluing the joining flap to the second side wall panel.
In order further to improve, or to be able further to improve, the gas- and/or liquid-tightness of the corner join with the method according to the invention it is advantageous according to the invention if the first panel fold line and/or the second panel fold line and/or the first top flap fold line and/or the second top flap fold line are crease lines, the groove of which, that is to say the depression, is located on the inside of the fold line concerned. This has the advantage that when folding about the respective fold line there is no bulging towards the interior of the box, which bulging would make it more difficult to produce a gas- and/or liquid-tight closure/seal at the corner join to be formed. In the case of the second panel fold line and the second top flap fold line such bulging would be able to impede flat contact of the joining flap with the second side wall panel, or could make this more difficult, which, as will be clear, increases the risk of the formation of a communication or connecting channel through to the bottom or top corner point between the second side wall panel and the joining flap. On corresponding grounds it is advantageous, at least in the case where the joining flap comes to lie inside the box, if the joining flap fold line is a crease line, the groove of which is located on the outside of the joining flap fold line, since this results in a clean outside fold curve which ensures that the joining flap fits well on the remainder of the blank when the box has been formed.
In order to be able to guarantee the seal between, on the one hand, the joining flap and the second side wall panel and, on the other hand, at least if present, between the second top flap and the first top flap with virtually 100% certainty and, at the same time, also to be able to ensure a robust join between the abovementioned parts, it is advantageous according to the invention if adhesive is spread over the entire overlap area and/or the overlap zone. Both in the case of the overlap area and in the case of the overlap zone, adhesive can be spread either on one side or on both sides with this procedure. In this context, spreading on one side is understood to mean that adhesive is spread on only one of the contact surfaces and spreading on both sides is understood to mean that adhesive is spread on both contact surfaces. In relation to spreading with adhesive it must also be pointed out that the adhesive coating concerned can be either a thin or a thick adhesive coating, depending on what the requirements will be under the circumstances.
So as to be able further to improve the gas- and/or liquid-tightness of the corner join, or at least to be able to improve the reliability thereof, it is advantageous according to the invention if the joining flap has been/is constructed such that when the corner join has been formed the bottom edge of the joining flap is in contact with or virtually in contact with the base panel. Correspondingly, in the case of a second top flap it is advantageous if the joining flap has been/is constructed such that when the corner join has been formed the top edge of said flap is in contact with or virtually in contact with the underside of the second top flap.
According to a second main aspect of the invention, which advantageously can also be used in combination with the first main aspect of the invention which has been discussed above, (i.e. the gas- and/or liquid-tight corner join of a box and the method for obtaining such a corner join), the invention relates to a method for obtaining boxes which breathe in a controllable manner, wherein the blank, from which the box is/has been made up, has been produced from solid cardboard, preferably solid board, with a core of, for example, grey board, and has been coated on one or both sides with a coating, for example of plastic, such as PE, which is impermeable to gas, especially air, characterised in that the coating has been/is provided with air passages which open into the part of the core located behind the respective air passages. Here the controlled or at least controllable breathing is obtained by providing the coating with air passages which open into the part of the core located behind the coating, in particular behind the passages made therein. With this arrangement the coating can be a layer stuck on in film form or a layer applied in some other way, for example by impregnation, such as, for example, a layer of plastic or of protein. For example, it is highly conceivable that a coating has been or is provided with micropores. In this way the permeability of the coating is adjustable by means of the selection of the micropores. The core is made of a material that is permeable to gas, especially air. In this way the coating is able to allow gas, especially air, to pass through via the air passages and the core is able to allow gas, especially air, to pass through via a diffusion process. A major advantage here is that there is no direct communication between the interior and the exterior of the box, so that a bellows-like pumping action, which would result in forced transport of gas, is not produced as a consequence of shocks and movement of the panels.
According to an advantageous embodiment, with this arrangement the air passages have been/are made in one or more side wall panels, preferably outside the overlap areas. In this way it is possible to prevent the permeability of the box as a whole, which, specifically with regard to the control of the atmosphere to specific desired conditions, must as far as possible be reliably adjustable, from being influenced by the load in the box, that is to say the filling placed therein, which filling will completely or partially cover the base and could thus influence the permeability of the base.
Advantageously the air passages will be scores in the blank extending through the coating as far as the core or will be obtained by making such scores. A major advantage of such a method is that it is then possible to work with a single type of coating, which in principle is impermeable to gas, the permeability via the box walls then being adjustable depending on the product to be packed in the box by making a larger or smaller number of scores, or at least scores having a larger or smaller effective surface area/effective length.
The length of the scores, viewed parallel to the blank surface, will in general be approximately 10 mm to approximately 50 mm.
So as to affect the vertical loading capacity of the box as little as possible by the scores, it is advantageous according to the invention if the scores extend transversely to the respective panel fold line. This means that when the box has been made up and scores have been made in the side wall or side walls thereof the scores will extend vertically.
In the case of a blank covered with coating on both sides it is advantageous according to the invention if the air passages on one side of the blank have been/are made offset somewhat with respect to the air passages on the other side of the blank. In the case of air passages in the form of scores, this means that the scores on one side have been offset somewhat transversely to their longitudinal direction with respect to the scores on the other side, the scores on either side then running parallel to one another. By adjusting said offset depending on the properties of the materials used in the blank, in particular the properties of the core and the product to be packed in the box, it is possible to meet the desired permeability requirements, which are dependent on the circumstances.
In order to prevent the core from disintegrating between the scores, in particular by a sort of delamination in the plane of the blank, it is advantageous according to the invention if the offset is at least 5 to 10 mm. So that transport is possible between adjoining scores made from either side, according to the invention the offset will in general be at most approximately 30 to 40 mm. With larger offsets, in particular offsets greater than 70 mm, the transport capacity by means of diffusion through the core material will decrease appreciably in view of the relatively large offset; the various aspects will be partly dependent on the material properties, such as the permeability of the core material.
Advantageously, the air passages per coating will have been made in accordance with one or more groups of matrix patterns. In the case of air passages being made on both sides, said matrix patterns will then have been made offset somewhat with respect to one another on either side.
According to the first main aspect of the invention, the invention furthermore also relates to a box provided with one or more corner joins obtained by the method according to the invention.
According to the first main aspect the invention furthermore also relates to a rectangular box having a rectangular base panel, having two transverse walls or longitudinal walls, each forming a first side panel, and having two longitudinal walls or, respectively, transverse walls, each forming a second side panel, wherein the box has been provided with four corner joins, each obtained by the method according to the invention.
According to the second main aspect of the invention, the invention also relates to a box obtained from a blank according to or obtained in accordance with one of Claims 20-28, wherein the box has an access opening, wherein the blank has been made up of blank sections joined via fold lines into one piece, wherein the joins of the blank sections to one another are essentially gas-tight and wherein the surface spanned by the blank is essentially closed. With this arrangement the blank sections can thus have been fixed to one another essentially gas-tight and preferably also essentially liquid-tight, in accordance with various methods, such that no or at least virtually no gas and/or liquid transport between the interior and the exterior of the box is possible via the fixings. With this arrangement the surface spanned by the blank will furthermore be essentially closed, that is to say no free, essentially unimpeded passages between the one side and the other side of one wall section, base section or lid of the box will be possible. The permeability of the box is then adjusted/obtained in a controlled manner by providing air passages in accordance with one or more of Claims 20-28.
Furthermore, in accordance with both the first main aspect and the second main aspect the invention relates to an assembly of a box according to the invention and a filling placed in the box, wherein the filling comprises a living product and/or vegetables and/or fish and/or meat and wherein the access opening to the box is closed in an essentially gas-tight manner or, if appropriate, in a manner such that controlled gas permeability via the closure of the access opening is possible. With this arrangement the access opening can be closed off using a transparent film, which can be fixed to the box around the edges of the access opening by means of adhesive or some other means. The film could, for example, be of gas-permeable construction, for example permeable via a diffusion process.
Both in accordance with the first main aspect and in accordance with the second main aspect, the invention also relates to the use of a box according to the invention for packing and/or storing and/or transporting living products and/or vegetables and/or fruit and/or meat and/or fish.
Likewise in accordance both with the first main aspect and with the second main aspect of the invention, the invention furthermore also relates to a box blank which in particular is suitable for use of the method according to both the first main aspect and the second main aspect of the invention, which box blank is provided with an essentially rectangular base panel, wherein a transverse end wall panel is joined via a first panel fold line to the base panel along each of two opposite first sides, wherein a longitudinal wall panel is joined via a second panel fold line to the base panel along each of the two other sides, which transverse wall panels and longitudinal wall panels form the wall panels when the box has been made up, wherein the transverse wall panels are joined to joining flaps via joining flap fold lines on opposite side edges, which joining flaps extend in the extension of the transverse and longitudinal wall panels when the blank is flat, wherein the joining flaps are in contact with the adjoining longitudinal wall panel in an overlap area in each case, when the box has been made up, characterised in that
such an adhesive pattern of adhesive has been applied to each joining flap and/or to each overlap area; and/or
a mastic-like filler, such as adhesive/said adhesive, has been so applied in the region of each overlap area in or on each adjacent second panel fold line that, in a box folded and made up from the blank, wherein each joining flap has been/is glued to an adjoining longitudinal wall panel, at least the corner point located at the point of intersection of the first panel fold line, the second panel fold line and the joining flap fold line is closed off towards the interior of the box by the adhesive in the adhesive pattern and/or the mastic-like filler.
With a box blank of this type the adhesive pattern and/or the filler, such as is required for, in particular, the first main aspect of the invention, can have already been applied beforehand to the blank such that each seam extending from said point of intersection has been closed off by the adhesive or, respectively, the filler.
With this arrangement the box blank can have been formed from solid cardboard, preferably solid board of the sandwich type, but the box blank can also have been formed from corrugated board.
In particular in connection with the second main aspect of the invention, the box blank will advantageously have been provided on at least one side, preferably on both sides, with a coating, in particular a layer produced from a gas- and/or liquid-tight material, in particular a plastic or a protein.
According to a further embodiment, in particular with regard to the second main aspect of the invention, the box blank has been advantageously provided on at least one side, preferably on both sides, with a coating, in particular a layer, produced from a gas- and liquid-tight material, in particular a plastic, wherein the coating has been provided with air passages in accordance with the invention (in particular one or more of Claims 20-28).
According to a third main aspect, derived from the second main aspect, the invention also relates to a method for packing living products. Such a method is disclosed in International Patent Publication WO 93/22138. Said third main aspect of the invention can very well be used in combination with the first main aspect and/or the second main aspect of the invention.
With said known method a box is folded from a flat blank made of corrugated board, which box has been provided with essentially gas- and liquid-tight walls and is closeable at the top with the aid of flaps which are closeable over the removal opening, or by means of a plate-shaped lid that can be fixed over the removal opening. The box is therefore gas- and liquid-tight. During use, living products, such as vegetables or fruit, are enclosed in the box and a gas or gas mixture that is essentially inert, such as a gas mixture containing a high concentration of nitrogen, is then introduced into the box. By this means gas exchange in the box as a result of the residual metabolism of the living products is essentially prevented, as a result of which the period for which the products can be packed in the box is extended. The walls of said known box have been provided with at least one layer of polyethene, such that a particular specific gas permeability is obtained, said permeability being chosen depending on the products to be packed and on the storage conditions. The polyethene layer is completely moisture-tight, so as to prevent the board from losing its strength and thus to prevent the box from losing its bearing capacity.
Said known method has the disadvantage that a gas or gas mixture having a particular specific composition has to be introduced into the box, which is technically complex, time-consuming and expensive and, moreover, can easily lead to mistakes. Moreover, such a gas mixture can adversely affect the moisture balance in such a packaging. A further disadvantage of said known method is that the box has to have a particular specific gas permeability, which, moreover, is highly dependent on the storage and use conditions. After all, if the living products are stored in the box at relatively high temperatures, the gas permeability can be higher, as a result of which the storage conditions in the box can become less good. Furthermore, said specific requisite gas permeability has the disadvantage that the box is suitable for only one application, as a result of which a large number of different boxes will be needed to be able to transport a wide variety of types of products to a wide variety of destinations.
According to a third main aspect, the aim of the invention is a method of the type described three paragraphs ago, with which the said disadvantages have been avoided, whilst retaining the advantages thereof. To this end a method according to the invention is characterised in that the products are placed in a box, such as a cardboard box, having gas- and liquid-tight walls, after which an access opening in the box is closed off by means of a closure, such as a film, preferably a transparent film, which box, when closed, is essentially gas- and liquid-tight except for micro-openings in at least a number of wall panels of the box, which micro-openings have been provided to allow permeation of gas and/or liquid through the wall panel or each wall panel concerned, wherein the micro-openings together have a surface area of less than 0.1%, more particularly less than 0.05%, of the total outer surface area of the box. With this arrangement an atmosphere in the box having at least a raised CO2 content can be produced and maintained by the residual metabolism of the living products packed in the box.
In contrast to the known method, with a method according to the invention a natural balance between the gases exists in the interior of the box, which balance is obtained as a consequence of the limited natural metabolism of the packed products. As a consequence of, inter alia, said natural metabolism, the relative atmospheric humidity inside the box will be able to increase to virtually 100% or, optionally, a lower desired value.
Loss of moisture from the packed products is suitably prevented from occurring by adjusting the atmospheric humidity inside the box to a relatively high level. This offers the advantage that less or even no excess weight has to be packed when filling the boxes since the packed products will at least virtually retain their initial weight during storage and transport. As a result, on balance, more economic use is made of the available volume, as a result of which storage and transport costs are even further reduced. Moreover, the quality of the packed product is better retained by this means.
Within the framework of all main aspects of the invention, living products must be understood to be all those natural products which in the packed state at least partially display a natural metabolism, by means of which exchange of at least oxygen with the environment takes place.
Under the influence of the said natural metabolism, the concentration of oxygen (O2) in the box falls and, at the same time, the concentration of carbon dioxide (CO2) in the box rises. By this means an atmosphere is created in which the products acquire a relatively long shelf life. The natural metabolism of the living products is suppressed. Moreover, the concentration of carbon dioxide in the box is prevented from becoming unacceptably high by the residual leakage that takes place.
In an advantageous embodiment a method according to the third aspect of the invention is characterised in that a box is used in which the micro-openings have a maximum width of less than 20 micrometers, more particularly an average width of between 10 and 20 micrometers.
Micro-openings of such a small width or cross-section have the advantage that moisture is not able to pass through said micro-openings unimpeded. Moisture will pass through the micro-openings only by, for example, capillary action or by suction action of the board located in or behind the micro-openings, as a result of which limited moisture transport through the wall of the box is possible. Moreover, the fact that gas transport, or at least gas migration through the wall of the box is possible through said micro-openings is of more importance for influencing the atmosphere in the box, in particular the O2/CO2 ratio. Such micro-openings are also the subject of the second main aspect of this invention.
Closing off the open side or access opening of the box with the aid of a, preferably flexible, film offers the advantage that said film is simple to fix on longitudinal edges of the box, whilst it takes up little space. By making the film transparent, the contents of the box can be inspected without the gas-tightness thereof having to be broken.
Making the micro-openings in the wall sections of the box offers the abovementioned advantages. Making said micro-openings by perforating the at least one coating with the aid of board fibers offers the advantage that no further steps for processing the board are required. The at least one coating needs to be applied only to one surface of the board of a suitable roughness, such that fibers will protrude through the coating. With this arrangement said fibers have the advantage that they will ensure capillary action.
Surprisingly, it has been found that micro-openings having a total surface area of, for example, 0.1% or less of the total outer surface area of the box lead at least to a particularly good gas and moisture balance inside the box, virtually unaffected by the ambient temperature. In this context micro-openings must be understood as also comprising damage to the coating, for example in the case of punch and fold lines.
In a further preferred embodiment a box according to the invention is characterised in that support columns have been formed in the corners of the box, preferably from the joining flaps by means of folding.
The support columns in the corners of the box offer the advantage that the box has high strength in the vertical direction, so that good stacking of filled boxes is possible. Folding of such support columns from the joining flaps offers the advantage that there are fewer seams, whilst, moreover, the complete box can then be folded from a single blank. The support columns offer the advantage that adequate bearing capacity is maintained even if the board becomes somewhat damp, whilst the boxes can nevertheless be placed close against one another by the side wall panels and/or end wall panels.